Tuesday, July 1, 2014

access to dialectResolutionInfo cannot be null when 'hibernate.dialect' not set

While I was trying JPA stuff on Spring Boot I had a "Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set" exception. I was using "spring-boot-starter-data-jpa" and everything seemed to be in place but still I was getting this. Later I realized that I did not include my database's dependency. After I added it to my pom the problem was fixed.



  postgresql
  postgresql
  9.1-901.jdbc4

Thursday, June 26, 2014

spring boot presentation

Yesterday I did a Spring Boot presentation at Sony Eurasia. Here are the slides:


Wednesday, June 4, 2014

spring social example on spring boot or how I stopped worrying and loved autoconfiguration

As of Spring Boot 1.1.0.RC1, autoconfiguration and the starter pom of Spring Social  is added which means that I won't have to add a hundred dependency to my pom and lots of meaningless Spring configuration will be handled for me. Let's see how it works on an example.

 I will implement a web application of two pages. One will show the given user's Twitter timeline and the other user's profile information. Here's my pom:



    4.0.0

    nr.co.caught
    BootTwitterJoy
    1.0-SNAPSHOT
    war

    
    
        org.springframework.boot
        spring-boot-starter-parent
        1.1.0.RC1
    

    
        
            org.springframework.boot
            spring-boot-starter-social-twitter
        

        
        
            org.apache.tomcat.embed
            tomcat-embed-jasper
        
        
            javax.servlet
            jstl
        

    

    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

    
    
    
        
            spring-snapshots
            http://repo.spring.io/snapshot
            
                true
            
        
        
            spring-milestones
            http://repo.spring.io/milestone
        
    
    
        
            spring-snapshots
            http://repo.spring.io/snapshot
        
        
            spring-milestones
            http://repo.spring.io/milestone
        
    


As you can see, I have my starter-social-twitter dependency which gives me Spring Social and Web capabilities. I'll add jasper and jstl for my jsp pages to work. My repositories part is quite populated due to the milestone repositories.
Now we will add our Service to do Twitter method calls and a Controller for handling the requests. Our Controller is plain and simple:
@Controller
public class TwitterController {

    @Autowired
    private TwitterService twitterService;

 @RequestMapping(value = "/timeline/{twitterUser}")
 public String getUserTimeline(@PathVariable String twitterUser, Model model) {
        model.addAttribute("tweets", twitterService.getUserTimeline(twitterUser));
        model.addAttribute("user", twitterUser);

  return "timeline";
 }

    @RequestMapping(value = "/profile/{twitterUser}")
    public String getUserProfile(@PathVariable String twitterUser, Model model) {
        model.addAttribute("userProfile", twitterService.getUserProfile(twitterUser));

        return "profile";
    }
}
If the request comes with "/timeline/username", our controller will get the user timeline and if it comes with "/profile/username" it will get the user profile from TwitterService. Here's our TwitterService:
@Service
public class TwitterService {

   @Autowired
    private Twitter twitter;

    public List < Tweet > getUserTimeline(String twitterUser) {
        TimelineOperations timelineOps = twitter.timelineOperations();
        List tweets = timelineOps.getUserTimeline("@" + twitterUser);

        return tweets;
    }

    public TwitterProfile getUserProfile(String twitterUser) {
        UserOperations userOperations = twitter.userOperations();
        TwitterProfile userProfile = userOperations.getUserProfile(twitterUser);

        return userProfile;
    }
}
We have a Twitter object that'll be created thanks to Spring Boot's autoconfiguration. We just have to provide an app id and app secret key (a.k.a. consumer key and consumer secret) in our application properties and Boot will do the rest. I'm quoting Twitter object explanation from Spring javadoc: "This instance of TwitterTemplate is limited to only performing operations requiring client authorization. For instance, you can use it to search Twitter, but you cannot use it to post a status update. The client credentials given here are used to obtain a client access token via OAuth 2 Client Credentials Grant". If you try to do a status update, you'll get "org.springframework.social.MissingAuthorizationException: Authorization is required for the operation, but the API binding was created without authorization". For further Twitter functionality, we would need to provide access token and access token secret keys as well but as far as I know autoconfiguration would not handle these cases yet.
My JSPs:
profile.jsp:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title></title>
</head>
<body>
<img src="${userProfile.profileImageUrl}"/>  
Screen name: ${userProfile.screenName}
Name: ${userProfile.name}
Description: ${userProfile.description}
Location: ${userProfile.location}
Followers: ${userProfile.followersCount}
</body> </html>
As you can see, profile takes the userProfile provided by our Controller and show the basic profile properties. timeline.jsp
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Time Line for <c:out value="${twitterUser}" /> TimeLine</title>
</head>
<body>
<ul>
    <c:forEach items="${tweets}" var="tweet">
        <li>${tweet.text}
at <c:out value="${tweet.createdAt}"/></li> <br/> </c:forEach> </ul> </body> </html>
Tweets are shown with their text and creation date. My application.properties content:
# Config for JSPs
spring.view.prefix: /WEB-INF/jsp/
spring.view.suffix: .jsp

# SPRING SOCIAL TWITTER (TwitterAutoConfiguration)
spring.social.twitter.appId= someAppId
spring.social.twitter.appSecret= someSecretId
spring.view properties are for the jsp handling. spring.social.twitter properties can be obtained from http://dev.twitter.com. Just login there with your twitter account, create your app and get your api keys. Here's the result:




You can check the code at github.

Thursday, May 29, 2014

exception after main class package change in spring boot

In my Spring Boot toy project ( web + mongodb), I want to change the structure of my packages. My old structure was like this:

Putting @ComponentScan annotation (without a base package) was fine for scanning all my classes. But when I update the structure and moved my main file (BootQeyfi) to launch package, I needed to update base package with
@ComponentScan(basePackages = "main") . After that definition Spring will scan the main as a base package and handle everything perfectly.

But of course that's not the case. I got the following exception which basically means "I could not autowire your repository class (your interface which extends MongoRepository)" 
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private main.service.HelloService main.controller.HelloController.service; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: main.dao.ProductRepository main.service.HelloService.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [main.dao.ProductRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
 at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
 at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
 at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
 at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:703)
 at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
 at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
 at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:120)
 at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:648)
 at org.springframework.boot.SpringApplication.run(SpringApplication.java:311)
 at launch.BootQeyfi.main(BootQeyfi.java:27)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private main.service.HelloService main.controller.HelloController.service; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: main.dao.ProductRepository main.service.HelloService.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [main.dao.ProductRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
 at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
 ... 14 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: main.dao.ProductRepository main.service.HelloService.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [main.dao.ProductRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
 at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
 at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
 at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
 at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
 at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
 ... 16 more
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: main.dao.ProductRepository main.service.HelloService.repository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [main.dao.ProductRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
 at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
 ... 27 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [main.dao.ProductRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1103)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:963)
 at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
 at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
 ... 29 more
To fix this problem, @EnableMongoRepositories must be added to your main class. My repository is under "main.dao" so my definition is like @EnableMongoRepositories(basePackages = "main.dao").

Sunday, May 25, 2014

rocking with mongodb on spring boot

I'm a fan of Spring Boot and here's my mongodb example project on Spring Boot. Most of the mongodb example projects are so basic that you won't go far with them. You can search for plain Spring Data examples but they can get much complex than you'd like. So here's mine.


Here's the pom I'll use.


    4.0.0

    caught.co.nr
    boottoymongodb
    1.0-SNAPSHOT
    war


    
    
        org.springframework.boot
        spring-boot-starter-parent
        1.0.0.BUILD-SNAPSHOT
    

    
        
            org.springframework.boot
            spring-boot-starter-data-mongodb
        

    

    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

    
        
            spring-snapshots
            Spring Snapshots
            http://repo.spring.io/snapshot
            
                true
            
        
    

    
        
            spring-snapshots
            http://repo.spring.io/snapshot
        
    

The only dependency I need is "spring-boot-starter-data-mongodb" which contains all necessary dependencies for a spring boot mongodb project. Next is the model for my collection. Document annotation points to my collection named "products". It is need only if your model name does not match your collection name. You can see a field annotation which maps the field name in the collection to the model's field name.

@Document(collection = "products")
public class Product {
    @Id
    private String id;
    private String sku;

    @Field(value = "material_name")
    private String materialName;

    private Double price;
    private Integer availability;


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSku() {
        return sku;
    }

    public void setSku(String sku) {
        this.sku = sku;
    }

    public String getMaterialName() {
        return materialName;
    }

    public void setMaterialName(String materialName) {
        this.materialName = materialName;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public Integer getAvailability() {
        return availability;
    }

    public void setAvailability(Integer availability) {
        this.availability = availability;
    }

    @Override
    public String toString() {
        return "Product{" +
                "id='" + id + '\'' +
                ", sku='" + sku + '\'' +
                ", materialName='" + materialName + '\'' +
                ", price=" + price +
                ", availability=" + availability +
                '}';
    }
}
Not we will need a DAO layer to manipulate my data. MongoRepository is the interface I should implement if I want to use autogenerated find methods in my DAO layer and I want that. Every field of my model can be queried with these autogenerated methods. For a complete list of method name syntax check here. My query below will take a sku name and search my collection for this name and return the matching ones.

public interface ProductRepository extends MongoRepository < Product, String >{
    public List < Product > findBySku(String sku);
}
Now I'll introduce a Service which will call my DAO interface. But wait a minute, I didn't implement this interface and wrote necessary code for fetching the models right? Yep, these methods are autogenerated and I don't need an implementation for this interface.
@Service
public class ProductService {
    @Autowired
    private ProductRepository repository;

    public List < Product > getSku(String sku){
        return repository.findBySku(sku);
    }
}
Next, lets launch our Boot example. Here's our main class:
@Configuration
@EnableAutoConfiguration
@ComponentScan
public class BootMongoDB implements CommandLineRunner {

    @Autowired
    private ProductService productService;

    private static final Logger logger = LoggerFactory.getLogger(BootMongoDB.class);

    public void run(String... args) throws Exception {
        List < Product > sku = productService.getSku("NEX.6");
        logger.info("result of getSku is {}", sku);
    }

    public static void main(String[] args) throws Exception {
        SpringApplication.run(BootMongoDB.class, args);
    }
}

If you have a connection to a mongodb instance and a sku matching to the name you searched than you should see one or more Products as a result. What we did was quite basic. What if I want more complex queries? For instance if I want a specific sku with an availability equal to "1"? I can't do it without using some @Query magic. So I'm updating my DAO class.
public interface ProductRepository extends MongoRepository < Product, String >{
    public List < Product > findBySku(String sku);

    @Query(value = "{sku: ?0, availability : 1}")
    public List < Product > findBySkuOnlyAvailables(String sku);
}
I provided a direct query for mongodb where sku in the signature of my method will be inserted to "?0" in the query and will be sent to mongodb. You can update your Service and then your main method to see if it works. You may not like writing queries which are not much readable if you're not very familiar with mongodb's syntax. Then this is the time for adding custom DAO classes. It's not possible to add and use methods other than the autogenerated ones to ProductRepository. So we will add few classes and have a nice featured methods. Our repository class was named "ProductRepository". We will add a new interface named "ProductRepositoryCustom" and a new method which will find available skus for the given name (twin of findBySkuOnlyAvailables method).
public interface ProductRepositoryCustom {
    public List < Product > findBySkuOnlyAvailablesCustom(String sku);
}
 
Then provide an implementation for this. Below you see that we inject ProductRepositoryCustom's mongotemplate and do stuff with it. We create two criteria. First one is for the sku name and the second one is for availability.
public class ProductRepositoryImpl implements ProductRepositoryCustom {
    @Autowired
    private MongoTemplate mongoTemplate;

    public List < Product > findBySkuOnlyAvailablesCustom(String sku) {
        Criteria criteria = Criteria.where("sku").is(sku).
andOperator(Criteria.where("availability").is(1));
        return mongoTemplate.find(Query.query(criteria), Product.class);
    }
}
The last step for custom implemetation is the update of ProductRepository class. As you can see below the only update I need is the addition of my ProductRepositoryCustom so we can link both of them together. All this naming can sound a little stupid. But notice that although the name of your custom interface is not important, a change in the name of the implementation will result in the throw of an exception:
Invocation of init method failed; nested exception is org.springframework.data.mapping.PropertyReferenceException: No property only found for type String! Traversed path: Product.sku.
To fix this make sure that the name of your implementation class is "ProductRepositoryImpl" which is the concatenation of the name of the interface that extends MongoRepository and "Impl".
public interface ProductRepository extends MongoRepository < Product, String>, ProductRepositoryCustom
If we add our new method to our Service layer:
@Service
public class ProductService {
    @Autowired
    private ProductRepository repository;

    public List < Product > getSku(String sku){
        return repository.findBySku(sku);
    }

    public List < Product > getAvailableSkuCustom(String sku){
        return repository.findBySkuOnlyAvailablesCustom(sku);
    }
}
Then update our main class' run method:
   public void run(String... args) throws Exception {
        List < Product > sku = productService.getSku("NEX.6");
        logger.info("result of getSku is {}", sku);

        List < Product > availableSkuCustom = productService.getAvailableSkuCustom("NEX.6");
        logger.info("result of availableSkuCustom is {}", availableSkuCustom);
    }
Again you must see something in the log :). You can check the whole project on github.